JPH021789B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to effective shrinkage reducing agents for cement. Conventionally, one of the serious drawbacks of cement mortar and concrete (hereinafter referred to as cement compositions) is that they are susceptible to dry cracking. This is due to the large drying shrinkage of cement. Therefore, it is desired to reduce drying shrinkage of cement compositions. Alkylene oxide adducts have been used as cement admixtures for various purposes. For example, polyoxyethylene alkylaryl ether (the number of carbon atoms in the alkyl group is usually 8 to 10, and the number of moles of ethylene oxide added is usually about 2 to 30 moles per mole of alkylphenol) is used as an air entraining agent for cement. It is used as an admixture for backfilling mortar, and as an emulsion stabilizer for latex mixed with cement. Polyoxyethylene/oxypropylene block copolymer (usually a polymer of about 30 to 250 moles of alkylene oxide)
is used as a dispersant for cement, a water reducing agent, etc.
In addition, higher alcohol alkylene oxide adducts (usually 5 to 30 moles of alkylene oxide adduct per mole of higher alcohol having 8 or more carbon atoms) are:
It is used as an air entraining agent for cement and as an emulsion stabilizer for latex mixed with cement. Furthermore, polyoxyalkylene glycol (a polymer of alkylene oxide, usually about 15 to 30 moles) is used as a dispersant for fibers mixed in cement such as asbestos and glass wool, and in combination with cement dispersants such as lignin sulfonic acid. It is used for the purpose of further increasing its dispersibility. The conventional alkylene oxide adducts used for the above-mentioned cement mixtures have a large number of moles of alkylene oxide added or are added to alkyl groups having a large number of carbon atoms, and these have poor dispersibility, It has the functions of a surfactant, such as foaming and wetting properties, or is used for the purpose of exhibiting that function. Such alkylene oxide adducts do not have an effect as an effective shrinkage reducing agent for cement, or even if they do, it cannot be said that they exhibit a sufficient effect. On the other hand, in order to reduce the drying shrinkage of cement compositions, a method of mixing latex such as acrylic latex or synthetic rubber latex into the cement composition is used, but in this case, relatively expensive latex is used. Since it is necessary to mix a large amount (for example, about 20 to 30% by weight based on the cement), it is not only economically undesirable, but also causes a fatal defect in that the strength of the cement composition is significantly reduced. Furthermore, the incorporation of a large amount of latex causes a serious drawback in that the nonflammability of the cement composition is impaired. Although inorganic expandable admixtures (for example, calcium sulfoaluminate-based expandable admixtures) have been developed in recent years, they are not sufficient to essentially reduce drying shrinkage. In addition, the present inventors also
It was discovered that the alkylene oxide adduct of a specific lower alcohol described in No. 56-51148 has an excellent effect of reducing shrinkage of cement.
In order to prevent dry cracking of the cement composition using the additive, the amount added should be slightly increased (for example, about 4 to 5% by weight based on the cement).
The need arose. Under such circumstances, the inventors have conducted extensive research into an effective shrinkage reducing agent for cement that does not have the above-mentioned drawbacks and can prevent dry cracking in cement compositions even when added in a smaller amount, and have developed the present invention. The invention has been achieved. That is, the present invention is based on the general formula (1) RO(AO) _o H (1) (wherein, R is an alkyl group having 1 to 7 carbon atoms or a cycloalkyl group having 4 to 7 carbon atoms, and A is a carbon number 2
-3 alkylene groups, n is a number from 1 to 10), and a fluorine-based surfactant or/and a silicone-based surfactant for effective shrinkage reduction in cement. It is a drug. The compound represented by the general formula (1) of the present invention is usually an aliphatic lower alcohol having 7 or less carbon atoms or a lower alcohol having a cycloalkyl group having 4 to 7 carbon atoms, and an alkylene oxide such as ethylene oxide or/and propylene oxide. This can be easily obtained by adding . In the general formula (1), R is an alkyl group such as a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a hexyl group, a cyclobutyl group, A cycloalkyl group such as a cyclopentyl group, a cyclohexyl group, or a methylcyclohexyl group. Among these alkyl groups and cycloalkyl groups, carbon atoms of 1 to 4 An alkyl group having 3 or 4 carbon atoms is preferred, and an alkyl group having 3 or 4 carbon atoms is most preferred. In the case of an alkyl group or a cycloalkyl group having 8 or more carbon atoms, the solubility in water is extremely reduced, and the effect of reducing shrinkage is also significantly reduced. Moreover, if a large amount of alkylene oxide is added for the purpose of obtaining sufficient water solubility, the function as a surfactant will be expressed and foaming will become high, which is not preferable. This is because when a compound with cellular properties is mixed with cement to form a cement composition, air is entrained in the cement composition, resulting in a significant decrease in the strength of the composition. It is. In general formula (1), (AO) represents an alkylene oxide residue. Here, A is an alkylene group having 2 to 3 carbon atoms, such as an ethylene group and/or a propylene group. Further, the number n of added moles of alkylene oxide represented by (OA) _o is preferably 1 to 10. When n is less than 1, the shrinkage reducing effect is small and the alcohol is highly volatile, so it cannot be used. When n is larger than 10, the shrinkage reducing effect becomes small and air is entrained in the cement composition, which is not preferable. The preferable range of n also differs depending on the type of alkylene oxide to be added. For example, when ethylene oxide is used as the alkylene oxide, it is preferable to add 1 to 5 moles of ethylene oxide per mole of lower alcohol from the viewpoint of shrinkage reduction effect, odor, air entrainment, etc.
That is, in this case, n is within the range of 1 to 5.
In addition, when propylene oxide is used,
Similarly, it is preferable to add 1 to 4 moles of propylene oxide per mole of lower alcohol from the viewpoint of shrinkage reduction effect, odor, air entrainment, etc. Further, when ethylene oxide and propylene oxide are used together as alkylene oxides, the number of moles added is usually 2 to 10 moles per mole of lower alcohol. Particularly when the number of moles added is within the range of 5 to 10 moles, the cement composition will have low foaming properties, giving good results to the cement composition. When using ethylene oxide and propylene oxide together as alkylene oxide, ethylene oxide (C ₂ H ₄ O)/propylene oxide (C ₃ H ₆ O)
It is preferable that the molar ratio is within the range of 0.2 to 5.0 from the viewpoint of low foaming and high shrinkage reduction effect. When two or more alkylene oxides are used together, either block addition or random addition can be adopted in the present invention, but block addition is more preferable from the viewpoint of shrinkage reduction effect, especially lower alcohols. Most preferred is a block addition method in which ethylene oxide is added after propylene oxide is added to. In the above case, the compound represented by the general formula (1) is a compound to which lower alcohol ethylene oxide and/or propylene oxide is added,
This compound is used as an alkylene oxide to co-add other oxides such as butylene oxide, styrene oxide, etc. with an alkylene oxide having 2 to 3 carbon atoms to an extent that does not impede the performance of the cement composition. 50
% by weight or less), and such compounds are also included within the scope of the present invention. The fluorine-based surfactant and silicone-based surfactant used in the shrinkage reducing agent of the present invention include cationic type, nonionic type, and anionic type, and any of these types can be used. A type is preferable from the viewpoint of reducing cement shrinkage, and a nonionic type is more preferable. The fluorine-containing surfactant may be any commercially available surfactant and is not particularly limited. Typical examples of cationic fluorosurfactants include compounds having a hydrophobic group consisting of a barfluoroalkyl group having 5 to 18 carbon atoms and a cationic hydrophilic group (e.g., quaternary ammonium base, etc.). There is.
For example, Florado FC manufactured by Sumitomo 3M Ltd.
-134, Megafuc F-150 manufactured by Dainippon Ink Chemical Co., Ltd., Surflon S-121 manufactured by Asahi Glass Co., Ltd., Sturgient 300 manufactured by Neos Co., Ltd., and Tohoku Fertilizer Co., Ltd. ) manufactured by Eftup EF-
123B, EF-Tup EF-132, etc.
A typical example of a nonionic fluorocarbon surfactant is a perfluoroalkyl group having 5 to 18 carbon atoms as a hydrophobic group, and a nonionic hydrophilic group (e.g.
There are compounds consisting of ethylene oxide adducts, etc.). For example, Florado FC-170C manufactured by Sumitomo 3M Co., Ltd., Megafuck F-142D, F-144D, F-171, F- manufactured by Dainippon Ink Chemical Co., Ltd.
177, Surflon S-141 manufactured by Asahi Glass Co., Ltd., Neos
Sturgient 200, 251 manufactured by Tohoku Fertilizer Co., Ltd., EF-121, EF-122A, EF- manufactured by Tohoku Fertilizer Co.
122B, EF-122C, EF-122A3, etc. Typical examples of anionic surfactants include a perfluoroalkyl group having 5 to 18 carbon atoms as a hydrophobic group, and an anionic hydrophilic group (e.g., sulfonic acid group, carboxylic acid group, phosphoric acid group). There are compounds consisting of ester groups, etc.). This includes Florado FC-95 manufactured by Sumitomo 3M Ltd.
FC-98, FC-126, FC-128, Megafuck F-110, F-113, F- manufactured by Dainippon Ink Chemical Co., Ltd.
120, F-812, F-191, Surflon S-111, S-112, S-113 manufactured by Asahi Glass Co., Ltd., Sturgient 100, 150 manufactured by Neos Co., Ltd., manufactured by Tohoku Fertilizer Co., Ltd. E-tops EF-102, EF-103, EF-112, EF-
Examples include 123A and EF-123B. In addition to the above, cationic, anionic, and nonionic surfactants are available from Daikin Industries, Ltd., Kanto Denka Co., Ltd., Du Pont, ICI, Hoechst, CIBA-
It is also commercially available from GEIGY companies, and these can also be used as the fluorine-based surfactant of the present invention. In addition, the silicone surfactant used in the present invention includes a polysiloxane with a hydrophobic group, a cationic hydrophilic group (for example, a quaternary ammonium base), a nonionic hydrophilic group (for example, an alkylene oxide adduct) ), and anionic hydrophilic groups (for example, sulfuric acid ester salts, phosphoric acid ester salts, carboxylic acid salts, etc.). In Japan, various products are commercially available from Toray Silicone Co., Ltd., Shin-Etsu Silicone Co., Ltd., Toshiba Silicone Co., Ltd., etc., and these various products can be used in the present invention. The amount of the shrinkage reducing agent of the present invention used varies depending on the number of carbon atoms in the alkyl group and the number of carbon atoms in the alkylene group of the compound represented by general formula (1), but is usually 0.3 to 3% by weight based on the cement. . If the amount used is less than 0.3% by weight, the shrinkage reducing effect will be low, while if it exceeds 3% by weight, the shrinkage reducing effect will increase with the amount added. Since cracking can be prevented, it is not actually necessary to add more than 3% by weight. The proportion of surfactant contained in the shrinkage reducing agent of the present invention is 0.25 to 2.5% by weight in the case of a soft surfactant.
For silicone surfactants, it is 2.5 to 25% by weight. The means for adding the shrinkage reducing agent effective to the cement of the present invention is the same as in the case of cement admixtures that are generally used, such as mixing an appropriate amount of the shrinkage reducing agent in the mixing water in advance, or It is possible to adopt a method such as adding an appropriate amount of the shrinkage reducing agent during kneading of a mixture consisting of cement, aggregate, and water. The shrinkage reducing agent of the present invention can be used in combination with other components (optional). Such optional ingredients include metal chlorides such as calcium chloride and sodium chloride, metal sulfates such as sodium sulfate, known cement hardening accelerators such as organic amines such as triethanolamine, alcohols, sugars, starch, and glycerin. , known cement hardening retardants such as sodium polyphosphate, known reinforcing steel rust preventive agents such as sodium nitrite and calcium nitrite, lignin sulfonic acid, oxycarboxylic acid, naphthalene sulfonic acid formalin condensate, melamine sulfonic acid formalin condensate. Various cement dispersants, such as known cement dispersants such as carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl starch, phosphorylated starch, and known cement pastes such as sodium alginate, can be used. The method for constructing mortar or concrete to which the shrinkage reducing agent of the present invention has been added may be the same as conventional methods, such as troweling, filling into formwork, spraying, and injection with a caulking gun. In addition, the curing methods include air dry curing, moist air curing,
Either underwater curing or heating accelerated curing (steam curing, autoclave curing, etc.) may be used, or these methods may be used in combination. When the shrinkage reducing agent effective for the cement of the present invention is added to the cement, the drying shrinkage can be significantly reduced compared to the case where no additive is added. Furthermore, the nonflammability of the cement composition is less likely to be impaired, and furthermore, even when added in a high amount (for example, on the order of several percent), the strength of the cement composition will not be significantly reduced. The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Example 1 As a surfactant, Megafac F-, a nonionic, fusogenic surfactant manufactured by Dainippon Ink Co., Ltd.
144D was mixed in an amount of 2% by weight with respect to various lower alcohol alkylene oxide adducts to provide an effective shrinkage reducing agent for the cement of the present invention. These shrinkage reducing agents were added to ordinary Portland cement in an amount of 1.5% by weight to obtain a cured cement mortar. For these cured mortar products and cured cement mortar products without additives, the shrinkage rate was measured using the dial gauge method of JIS A 1129, and the strength was measured using JIS R 5201.
1 result was obtained. In addition, the measurement of air volume is based on JIS A
1128, measured as concrete. In addition, in the case of the mortar whose shrinkage rate and strength were measured, the water/cement ratio was 65% and the sand/cement ratio was 200%.
%. The concrete measured for air content had a unit cement content of 300 kg/m ³ , a water/cement ratio of 60%, and a fine aggregate percentage of 44%. As the ordinary Portland cement, Asano ordinary Portland cement manufactured by Nippon Cement Co., Ltd. was used.

[Table] Example 2 As a surfactant, nonionic silicone surfactant SH-3749 manufactured by Toray Silicone Co., Ltd.
It was mixed with n- _C4H9- ( _C2H4O ) _3H at a concentration of 10% by weight to provide _an effective shrinkage reducing agent for the cement of _the present invention. The shrinkage rate and strength were measured in the same manner as in Example 1 by changing the amount of this shrinkage reducing agent added to ordinary Portland cement, and Table 2
The results were obtained.

[Table] Example 3 n-C ₄ H ₉ -(C ₂ H ₄ O) ₃ H was used in an amount of 1.5% by weight based on the cement, various fluorocarbon surfactants were used at 200 ppm based on the cement, or silicone based surfactants were used at 200 ppm based on the cement. Blend at 0.1% by weight based on cement,
The shrinkage rate and strength were measured in the same manner as in Example 1, and the results shown in Table 3 were obtained. Table 3 also shows the results when a fluorine-based surfactant and a silicone-based surfactant were used alone as comparative examples.

[Table] Example 4 n-C ₃ H ₇ (-C ₂ C ₄ O) ₃ H was used in an amount of 1.5% by weight based on ordinary Portland cement, Florard FC-170C was used as a futsuo-based surfactant, and silicone-based surfactant was used. A test was conducted in the same manner as in Example 1, using SH3746 as the agent and changing the amount added.
The results shown in Table 4 were obtained.

【table】

【table】

Claims (1)

[Scope of Claims] 1. General formula (1) RO(AO) _o H...(1) (wherein, R is an alkyl group having 1 to 7 carbon atoms or a cycloalkyl group having 4 to 7 carbon atoms, A has 2 carbon atoms
-3 alkylene groups, n is a number from 1 to 10), and a fluorine-based surfactant or/and a silicone-based surfactant, effective for cement. Shrinkage reducer. 2 The compound represented by general formula (1) has the following general formula
(2), (3) and (4) RO (C ₂ H ₄ O) _{1 ~ 5} H ... (2) RO (C ₃ H ₆ O) _{1 ~ 4} H ... (3) RO (A ₁ O ) _2~10 H...(4) (wherein, R is an alkyl group having 1 to 7 carbon atoms or a cycloalkyl group having 4 to 7 carbon atoms, (-A ₁ O) - _2~10
is a polyoxyalkylene group consisting of C ₂ H ₄ O and C ₃ H ₆ O and having a mole number of 2 to 10). An effective shrinkage reducer for cement. 3. The shrinkage reducing agent effective for cement according to claim 1 or 2, wherein in general formula (1), R is an alkyl group having 1 to 4 carbon atoms. 4. The shrinkage reducing agent effective for cement according to claim 1, 2, or 3, wherein in the general formula (1), R is an alkyl group having 3 or 4 carbon atoms. 5 Claims 2 and 3, wherein the molar ratio of C ₂ H ₄ O/C ₃ H ₆ O in (-A ₁ O)- of the compound represented by general formula (4) is 0.2 to 5.0. or a shrinkage reducing agent effective for the cement according to any of paragraph 4. 6. The shrinkage-reducing agent effective for cement according to any one of claims 1 to 5, wherein the fluorine-based surfactant and/or the silicone-based surfactant are cationic or nonionic. 7. The shrinkage-reducing agent effective for cement according to any one of claims 1 to 6, wherein the fluorine-based surfactant and/or the silicone-based surfactant are nonionic.